Activity of Oral Amoxicillin, Ampicillin, and Oxytetracycline against Infection with Chlamydia trachomatis in Mice

The effects in mice of oral treatment with amoxicillin, ampicillin, and oxytetracycline against an otherwise lethal intranasal infection with Chlamydia trachomatis (mouse pneumonitis) were studied. When treatment was started 30 min after infection and continued once daily thereafter for a total of seven treatments, the mean protective doses of amoxicillin, ampicillin, and oxytetracycline were 9.5, greater than 50, and 31.3 mg/kg, respectively. If 14 oral treatments were given, these values were 1.6 mg/kg for amoxicillin, 12.7 mg/kg for ampicillin, and 12.3 mg/kg for oxytetracycline.